Electric circuit breaker of the gas-blast type



Dec. 12, 1944. n. F. AMER ETAL ELECTRIC CIRCUIT BREAKER OF THE GAS-BLAST TYPE Filed Sept. 29, 1942 2 Sheets-Sheet 1 Inventor B ma; -.u qwwta,

Attorney 5 Dec. 12, 1944. D. F. AMER ETAL 2,365,134

ELECTRIC CIRCUIT BREAKER OF THE GAS-BLAST TYPE Filed Sept. 29, 1942 2 Sheets-Sheet 2 Inventor Dem &%\@mm Attorney S Patented Dec. 12, 1944 UNITED STATES ELECTRIC CIRCUIT BREAKER OF THE. GAS-BLAST TYPE Donald Foster Amer, Newcastle-on-Tyne, England Application September 29, 1942, Serial No. 460,162

In Great Britain April 15, 1940 10 Claims.

This application is a continuation-in-part of the present applicants copending United States of America application Serial No. 388,700, now Patent No. 2,302,592, granted November 1'7, 1942.

The invention relates to an electric circuitbreaker of the kind in which a blast of deionising gas is caused to flow through a nozzle or vent to assist in extinguishing the arc. In such circuitbreakers the are is usually drawn out by relative movement of the arcing contacts of the circuitbreaker, but for eflicient operation it is desirable for the nozzle to be of relatively small size and this gives rise to difliculty in cases where the normal current-carrying capacity required involves comparatively large contact surfaces.

The present invention has for its object to avoid this difiiculty and at the same time to afiord increased speed and certainty of operation.

The circuit-breaker according to the invention comprises arc-initiatin contacts which are located on the high pressure side of the nozzle or vent and by whose separation the arc is initially formed, an arcing contact which is supported from the high pressure side of the nozzle or vent and is connected to one terminal of the circuitbreaker and to which one root of the arc is transferred by the gas-blast from the arc-initiating contacts, the arc when so transferred extending from such arcing contact towards the low pressure side of the nozzle or vent, and an auxilia y electrode located on the low pressure side of the nozzle or vent and connected through a resistance to one terminal of the circuit-breaker.

The second arcing contact to which the other root of the arc is transferred bythe as-blast may be arranged in various ways. Thus this contact may be constituted by the low pressure end of the nozzle or by a contact mounted therein and connected thereto or by a contact mounted near the nozzle or vent on the low pressure side thereof, and in such cases the auxiliary electrode may conveniently be disposed on the low pressure side of the second arcing contact and connected through the resistance to the first arcing conact.

There may however be two nozzles in axial alignment andthe gas-blast may be constituted by two streams of gas flowing towards one another respectively through the two nozzles and discharging outwardly between the nozzles, each nozzle having an arcing contact supported from its high pressure side and aset of arc-initiating contacts located on its high pressure side, whilst a single auxiliary electrode is located in the low pressure zone between the nozzles and is con- (Cl. 20i)148) nected through the resistance to the arcing contact sup-ported from the high pressure side of one of the nozzles.

The separating movement of the arc-initiating contacts or of each set of arc-initiating contacts may take place in a direction transverse to the length of the arc in the transferred position or in a direction substantially parallel thereto.

The invention may be carried into practice in various ways, but some convenient alternative arrangements according thereto are illustrated by way of example in the accompanying drawings. in which Figure 1 is a somewhat diagrammatic longitudinal section through one construction,

Figures 2 and 3 are longitudinal and transverse sections through a modified construction,

Figure 4 illustrates another modified construction, and

Figure 5 shows a further alternative employing two breaks in series.

In the construction of Figure 1, the circuitbreaker contacts are enclosed within an insulating casing A of generally cylindrical shape, 1

and at a suitable point in the len th of the casing is mounted a metal housing B containing a nozzle B which may be of insulating material or of metal. Gas under pressure can be admitted, when required, from a suitable reservoir into one end of the casing A. whilst the other end serves for the discharge of the arc gases, the nozzle 13 diverging towards the discharge end.

On the high pressure side of the nozzle a rod is mounted in axial alignment with the nozzle, the end C of this rod constituting one of the fixed arcing contacts of the circuit-breaker. Surrounding this rod C and connected to it by webs D is a tube D constituting the fixed arc-initiating contact, the arrangement being such that part of the gas-blast can flow between the rod C and the tube D. Although this arrangement is usually preferable, the rod and tube may. if desired, be rep-laced by a simple rod or tube serving both as arcing contact and as arc-initiating contact.

The moving arc-initiating contact is consti' tuted by a bridging contact E in the form of a group of inwardly spring-pressed contact fingers engaging with the tube D and is operated by the action of the gas-pressure on a piston E carried. by the bridging contact. These parts may be arranged in various ways. Thus the movement of the bridging contact may take place in the transverse direction (as shown. in the constructions of Figures 2 to 5) or alternatively, as in Figure 1, the ovement may take place in a direction parallel to the nozzle axis, preferably towards the discharge end of the casing A. Thus in the construction of Figure 1 the piston E slides on the inner surface B of the metal housing 13 under the control of the gas pressure against the action of a spring E and the bridging contact E en.- gages with an external surface 13 on the nozzle B and always remains in contact therewith.

Thus in the normal closed position of. the. circuit-breaker the bridging contact E serves to connect the tube D, which is connected to one of the circuit-breaker terminals D with the metal housing B to which the other circuit-breaker terminal B is connected, the metal housing in.

turn being connected to a second fixed arcing contact in the low pressure zone.

itself, the nozzle in this case being of. conducting material, or alternatively by a separate contact (indicated in, dotted line at B which may be mounted in the low pressure end of the nozzle or near thereto in the discharge passage. Such separate contact B may be centrally mounted on webs in the nozzle or in. a part of the metal housing beyond the nozzle, or may consist of a bar extending diametrically across the nozzle or the low pressure zone beyond it (as for example is shown in Figures 2 and 4). When such separate contact is employed the nozzle B may be of insulating material or of conducting material.

Mounted in the discharge passage at a suitable distance beyond the second fixed arcing contact is an auxiliary electrode F, which may consist (as shown) of a central electrode supported on webs F in the main casting A or (as in Figures 2 and 4) of a bar extending across the casing. This auxiliary electrode F is connected by a resistance F to the first fixed arcing contact C such resistance (shown diagrammatically in the drawings) conveniently being housed in a recess in the insulating Wall of the main casing A and being insulated from the metal housing B and the second fixed arcing contact.

Thus in the normal closed position of the circuit-breaker the bridging contact E completes the circuit between the arcing contact tube D and the metal housing B and the auxiliary electrode F performs no useful function. It will be clear that the contact surface area to suit any required normal current-carrying capacity can readily be provided by suitably arranging the bridging contact fingers without alteration of the size of the nozzle or other associated parts;

When it is desired to open the circuit-breaker, gas under pressure is admitted. into the casing A, and acts on the piston E to effect the separating movement of the arc-initiating contacts, the are being drawn out in the transverse direction or parallel to the axis, as the case may be. Immediately the are forms, the gas-blast acts on it and tends to, blow it through the nozzle B, as the result of which one are root. will establish itself on the first fixed arcing contact formed by the end C of the central rod C, whilst the other arc root will, if the nozzle is of conducting material, first be transferred to the high pressure end of the nozzle and will thence travel along the nozzle surface to the low pressure end thereof and will establish itself on the second fixed, arcing contact. If the nozzle is of insulating material the arc willv loop through the nozzle until it comes into contact with the second fixed arcing contact B whereupon part of the arc will The auxiliary electrode F does not come into full operation until after the arc has gone out, its primary purpose being to control any restriking of the arc. Thus the gas-blast will have swept some of the ionized gases from the arc into the space between the second arcing contact and the auxiliary electrode and will thus form a, possible current path between them in parallel with the arc gap between the arcing contacts, the resistance F being in series with such current path. The parts are so dimensioned that any restriking of the arc will take place between the second arcing contact and the auxiliary electrode F, and the current in such am will be limited by the resistance F and will in. the case of. an A.. C. circuit-breaker be at unity power factor, so that the arc will be readily and easily extinguished by the gas-blast.

The foregoing arrangement may be modified in various ways other than those above mentioned. Thus, if desired, the nozzle may be replaced by a simple restricted aperture in a disc, such disc being of insulating material or of conducting material connected to a separate arcing contact on the low pressure side. One such arrangement is shown in Figures 2 and 3, where in as above mentioned a lateral arc-initiating movement is used. In this arrangement the rod. tube and bridging contact are replaced by a fixed arc-initiating contact G in the form of a number of flat spring contact fingers engaging with a mov able knife blade contact H connected to a piston H acted upon by the gas-blast against the action of a spring H to move transversely with respect to the axis of the nozzle or vent, which is in the form of a restricted aperture J in a disc J mounted across the main casing A. In the example illustrated this disc J is of metal and is connected to the fixed contact G, whilst the second arcing contact is in the form of a bar K, extending across the casing A on the discharge side of the aperture J in the direction of movement of the knife blade H and is likewise connected to. the fixed contact G. The auxiliary electrode. L is also in theform of a bar parallel tothe bar K and on the discharge side thereof, and is .connected through a resistance L to the knife blade contact H. The operation of this arrangement will be clear from the description given above in respect of Figure 1.

Figure 4 shows another modification, in which the discharge passage is formed in a lateral branch M of the main cylindrical casing A, with the nozzle or equivalent restricted aperture J carried by a suitableinsulator M in such lateral branch. The arrangement of the apertured disc J the arcing contact bar. K and the auxiliary electrode, L are. generally analogous to those of Figures 2 and 3, and Figure 4 shows a convenient housing for the resistance L between the in sulator M and the insulating wall of the lateral branch M The resistance L is connected to one of two fixed arcing tips N N, and the apertured disc J. and second arcing electrode K are connected to the other. A bridging contact member N, which can move along the main insulating casing A under the action of the'gas blast, normally connects the two arcing tips together but breaks such connection when moved by the blast, so that the are initially forms between the two arcing tips and is blown through the aperture J on to the second arcing contact K so that it extends from the arcing tip B to the second arcing contact K, the auxiliary electrode L coming into full action as above described in the event of any restriking of the are.

In a further alternative arrangement, shown diagrammatically in Figure 5, there are two nozzles O O in axial alignment, the nozzles diverging towards one another, so that the two gas streams flow towards one another through the nozzles and discharge outwardly from the low pressure zone between them. Each nozzle is provided on its high pressure side with a fixed arcing contact and with arc-initiating contacts, such contacts being arranged with respect to the nozzle in one or other of the ways above described. In the actual example illustrated, a simple rod P (or P) serves both as fixed arcing contact and as fixed arc-initiating contact, and the moving arcinitiating contact Q (or (9}) moves laterally under the action of the gas-blast against spring pressure. The two moving arc-initiating contacts Q Q are connected together by a connection Q so that the two breaks are in series, the rods P P being respectively connected to the circuitbreaker terminals indicated at P P. The arcing contacts constituted by the ends of the rods P P on the high pressure sides of the nozzles cooperate with a single auxiliary electrode B, in the low pressure zone, this electrode being connected to the arcing contact P through a resistance R Thus when gas under pressure is introduced simultaneously at both ends, the two gas streams respectively cause the two sets of arc-initiating contacts to open and blow the arcs through the nozzles O so that they impinge on the auxiliary electrode R, thereby in effect making up a single are extending between the two arcing contacts P P through the two nozzles. Any restriking of the arc Will take place between the auxiliary electrode R and that one P of the arcing contacts to which the resistance R is not connected, and complete extinction of the arc will readily and quick y follow. The fact that the resistance R 1 is connected across part of the are before the arc goes out will also assist in limiting the are energy and thus facilitating extinction of the are.

It will be appreciated that the foregoing ex-- amples have been. described by way of example only and that the iinvention can be carried into practice in other ways.

What I cla m as my invention and desire to secure by Letters Patent is:

1. An electric circuit breaker comprising in combination a nozzle of conducting material through wh ch a blast of deionising gas flows to assist in extinguishing the are, a pair of arcinitiating contacts constituted respectively by a fixed conducting tube disposed substantially'in alignment with the nozzle on the high pressure side thereof by a bridging contact member normally connecting such tube with the nozzle but axially movable to break such connection, a fixed arcing contact constituted by a rod disposed within and electrically connected to the tube,-

second arcing contact disposed in the low pressure zone with respect to the nozzle, means for separating the arc-initiating contacts and thereby drawing out an are between them, such are being transferred by the gas-blast from the arc-initiating contacts to the arcing contacts so that when so transferred it extends generally centrally through the nozzle, an auxiliary electrode mounted on the low pressure side of the second arcing contact and insulated therefrom, and a resistance through which such auxiliary electrode is connected to the arcing contact rod.

2. An electric circuit-breaker, comprising in combination two nozzles in axial alignment, means whereby a blast of deionising gas for assisting in extinguishing the arc is caused to flow in two streams directed towards one another respectively through the two nozzles and to discharge outwardly from the low pressure zone between the nozzles, two sets of arc-initiating contacts respectively on the high pressure sides of the two nozzles, means for connecting the two sets of arc-initiating contacts in series with one another, two arcing contacts respectively supported from the high pressure sides of the two nozzles, means for separating the arc-initiating contacts and thereby initially drawing out two arcs in series, such two arcs being transferred by the gas-blast so that they merge into a single are extending between the two arcing contacts, an auxiliary electrode located in the low pressure zone between the nozzles adjacent to the path of the transferred arc, and a resistance through which such auxiliary electrode is connected to one of the arcing contacts.

3. An electric circuit-breaker as claimed in claim 2, in which the fixed arc-initiating contact associated with each nozzle is constituted by a rod-like member disposed substantially in axial alignment with the common axis of the nozzles, and the associated arcing contact is constituted by the end of such member.

4. An electric circuit-breaker as claimed in claim 2, in which the nozzles are made of conducting material insulated from the arcing contacts.

5. An electric circuit-breaker as claimed in claim 2, in which the two arcing contacts are fixed in position.

6. An electric circuit-breaker as claimed in claim 2, in which the separating movement of the arc-initiating contacts takes place in a direction transverse to the common axis of the nozzles.

7. An electric circuit-breaker as claimed in claim 2, in which the separating movement of the arc-initiating contacts is brought about by the pressure of the gas-blast against spring action.

8. An electric circuit-breaker as claimed in claim 2, in which the nozzles are made of conducting material insulated from the arcing contacts, and the two arcing contacts are each constituted by the end of a rod-like member disposed substantially in axial alignment with the nozzles.

9. An electric circuit-breaker as claimed in claim 2, in whicheach set of arc-initiating contacts comprises a fixed contact in the form of a rod-like member disposed substantially in axial alignment with the nozzles, a cooperating moving contact movable transversely to the length of such member, a piston carried by the moving contact and exposed to the pressure of the gas-blast, and a spring normally tending to hold the cooperating contacts in engagement.

10. An electric circuit-breaker, comprising in combination a restricted vent of conducting material through which a blast of deionising gas flows to assist in extinguishing the are, at least three contacts associated with the vent of which two constitute relatively movable arc-initiating 4 aseama contacts located on the high pressure side of the vent and of. which two constitute arcing contacts, one supported from the high pressure side. of the vent and the other located in the low pressure zone with respect thereto, yielding means displaceable by the gas-blast for causing the arcinitiating contacts to separate in a direction transverse to the direction of gas flow through the vent and thereby drawing out an arc between them, suchare being transferred by the gas- 10 blast from the arc-initiating contacts to the arcin: contacts so that when so transferred it extends generally centrally through the vent, an auxiliary electrode mounted on the low pressure side of the vent, and a resistance through which such auxiliary electrode is connected to the arcing contact supported from the high pressure side, the auxiliary electrode being insulated from the second arcing contact.

DONALD FOSTER AMER. 

